Hydraulic fracturing operations have increased, first in the United States of America and then in Canada, and will be expanded into countries such as China, Poland, Germany and England.
These operations, over the years, have become increasingly complex, being applied to increasingly lengthy horizontal drillings, so as to increase the production per well.
In principle, it consists in fracturing the in-place rock by injections of water at very high pressure (200 to 600 bar), in blocking the fractures by the injection of a propping agent, such as, for example, sand or ceramic, and in extracting the gas or oil therefrom.
Additives have been developed in order to make possible these fracturing operations in a safe and efficient manner.
Mention may be made, among these additives, of:                Friction reducers, which make it possible to obtain a pressure at the well bottom with lower injection pressures and lower pumping powers. These are polyacrylamides (PAMs), in the majority of cases in the conventional form, of emulsions. However, today, demand is focusing on powdered polyacrylamides and the Applicant Company has developed various materials which allow them to be efficiently employed on field.        Viscosifying agents, which are used to hold the sand in suspension and which are in the majority of cases guar gums. However, in the face of the shortage of guar, some other products have been used or are in the course of development: xanthan gums, polyacrylamide, and the like. Guar gums by nature are difficult to employ on field, because of their tendency to form agglomerates on contact with water which are very difficult and very time-consuming to dissolve. Conventionally, guar gums are suspended in a hydrocarbon and subsequently transported to fields, where they are dissolved in the injected water.        Crosslinking agents, such as borates, zirconates or titanates, which are used to crosslink guar gum so as to increase its viscosity and to prevent the sedimentation of the sand at a low pumping rate or during a shutdown.        
The most important ingredients by volume are guar gum and polyacrylamide, which both exhibit dissolution difficulties.
This problem can be solved with the use of a dissolution unit referred to as “PSU” (Polymer Slicing Unit) described in Patent U.S. Pat. No. 8,168,871.
Subsequently, the Applicant Company described a mobile system for dissolving polyacrylamides in a large amount in Application WO 2010/010698, taking into account sizes and weights allowed between two fracturing operations.
Although the items of equipment mentioned above are effective, they do not take into account the following issue increasingly encountered by gas and oil operators.
One of the problems encountered in hydraulic fracturing operations today is the complexity of the management of the streams of the different products injected and the consequence with regard to the profitability of such operations. Various items of equipment are used to transport, dissolve, meter out and inject these products into the mixer which supplies the very-high-pressure injection pump. These items of equipment are often disparate and have to be connected separately to the control centre which decides dosages as a function of the fracturing parameters measured. One of the objectives is thus to reduce and concentrate as much as possible the items of equipment necessary.
Another issue is that today guar gum is suspended in a hydrocarbon using surfactants in order to be transported on field in liquid form and dissolved by mixing with water with vigorous stirring. This operation results in the use of ingredients which will subsequently be additional contaminants in the water treatment. The dispersion and dissolution in-place is thus a major advance in fracturing operations.